27" iMac won't turn on after power failure overnight

Several days ago, I left it with sleep, and yesterday I pulled the cord out. Then the machine won't start up anymore. It doesn't have any chime or HDD start voice. I checked the forum and tried reset the SMC and RAM and even switched a plug, but it still doesn't work. Could anybody give me some advice on this? Since apple said it won't under warranty anymore for I add a SSD to my Imac last year.Thank you in advance.

A power supply issue could cause this situation. However, if the cord was simply unplugged when it was asleep, it shouldn't have done any damage. I'd try the SMC reset again, and plug something else into the socket where you plug in the Mac to double check it has power.

It would be not covered by warranty only if it's more than a year from purchase (without AppleCare), or you caused damage leading to the problem when installing the SSD. If it's still within the warranty period, and you are sure you didn't damage the iMac with the aftermarket install, then make an appointment (by calling AppleCare) for them to check it out. You could remove the SSD before this if you choose. But, if damage was caused, they'll find it. If not, they'll repair it, or if its out of warranty, give you an estimate.

When you press the power-on button, do you get ANY response at all? LED on, but nothing else? Do you hear anything happening inside? Anything at all? (aside: sometimes the power-on button itself doesn't make proper contact, or breaks)

Some things to try (again, may help, may not):

- With the iMac plugged in, press the power-on button and KEEP HOLDING IT DOWN a little while. Does anything change?

- Unplug the iMac. Hold down the power-on button, and while STILL HOLDING IT DOWN, plug the iMac into the wall outlet. Does anything change?

- I'm not sure if this is true for modern iMacs, but back in the earlier days of desktop Macs, a dead motherboard battery could prevent the computer from starting up when the power-on button was pressed. Replace the little battery, and everything was back to normal.

Hmmmm -- see that you installed an SSD into it. Do you have the original drive? Could you remove the SSD (temporarily) and then re-install the original drive in its original place? Does anything change?

Others will disagree with the following advice, but it's kept me going for 26 years on Macs:
Don't sleep the machine at night. Shut it down.
Get a power strip or surge protector. Connect it to the wall and connect the Mac to the surge protector. After you shut off the Mac, reach down and shut off the surge protector, as well.
In the morning, turn the surge protector on, then press the Mac's power-on button.

Get a power strip or surge protector. Connect it to the wall and connect the Mac to the surge protector. After you shut off the Mac, reach down and shut off the surge protector, as well.
In the morning, turn the surge protector on, then press the Mac's power-on button.

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Don't quite understand the reasoning behind shutting off the surge protector. Wouldn't you still want that active in case there is a power outage then power resumption to the house that could cause a spike coming through anything that is plug in to any socket in the house? Isn't that the point of a surge protector?

A power supply issue could cause this situation. However, if the cord was simply unplugged when it was asleep, it shouldn't have done any damage. I'd try the SMC reset again, and plug something else into the socket where you plug in the Mac to double check it has power.

It would be not covered by warranty only if it's more than a year from purchase (without AppleCare), or you caused damage leading to the problem when installing the SSD. If it's still within the warranty period, and you are sure you didn't damage the iMac with the aftermarket install, then make an appointment (by calling AppleCare) for them to check it out. You could remove the SSD before this if you choose. But, if damage was caused, they'll find it. If not, they'll repair it, or if its out of warranty, give you an estimate.

Click to expand...

Thank you for your explanation first. I take it for power supply problem too. Usually, just unplug the cord would not cause this situation. since i have done it like that for many times. The socket do has the power after my test. After I tried all of the ways posted on Internet, I decide to buy a Power Module and replace it by myself. I asked Apple store about this situation, they said it would be much cost since I removed the CD-Drive to save the space for SDD.

When you press the power-on button, do you get ANY response at all? LED on, but nothing else? Do you hear anything happening inside? Anything at all? (aside: sometimes the power-on button itself doesn't make proper contact, or breaks)

Some things to try (again, may help, may not):

- With the iMac plugged in, press the power-on button and KEEP HOLDING IT DOWN a little while. Does anything change?

- Unplug the iMac. Hold down the power-on button, and while STILL HOLDING IT DOWN, plug the iMac into the wall outlet. Does anything change?

- I'm not sure if this is true for modern iMacs, but back in the earlier days of desktop Macs, a dead motherboard battery could prevent the computer from starting up when the power-on button was pressed. Replace the little battery, and everything was back to normal.

Hmmmm -- see that you installed an SSD into it. Do you have the original drive? Could you remove the SSD (temporarily) and then re-install the original drive in its original place? Does anything change?

Others will disagree with the following advice, but it's kept me going for 26 years on Macs:
Don't sleep the machine at night. Shut it down.
Get a power strip or surge protector. Connect it to the wall and connect the Mac to the surge protector. After you shut off the Mac, reach down and shut off the surge protector, as well.
In the morning, turn the surge protector on, then press the Mac's power-on button.

Several days ago, I left it with sleep, and yesterday I pulled the cord out. Then the machine won't start up anymore. It doesn't have any chime or HDD start voice. I checked the forum and tried reset the SMC and RAM and even switched a plug, but it still doesn't work. Could anybody give me some advice on this? Since apple said it won't under warranty anymore for I add a SSD to my Imac last year.Thank you in advance.

Click to expand...

I would persevere with the "hold down the power button whilst plugging in the iMac" approach.

I'd leave the machine unplugged for a good 30 minutes, then press and hold the power button for a good minute. And finally, whilst still holding the power button down, plug it in.

I suspect it will power up, with the fans running on full. But if it does, you can at least from there do an SMC reset etc and get it back to normal.

It is of course possible that the PSU has died, but that would be pretty unusual for a power cut to do that.

You said you had installed an SSD. Did you do this yourself? I ask because if you did, you're familiar with getting inside.

If this is the case, I'd investigate what kind of motherboard battery is used in that model, then get ahold of one, and install it. Or at the very least, check the existing motherboard battery for voltage.

You said you had installed an SSD. Did you do this yourself? I ask because if you did, you're familiar with getting inside.

If this is the case, I'd investigate what kind of motherboard battery is used in that model, then get ahold of one, and install it. Or at the very least, check the existing motherboard battery for voltage.

Although it could very well be a bad power supply...

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HI, Thanks too.

I had tried all of the ways and decided to replace a Power module. And it worked.

For iMac, I dismantled it for several times and very familiar with the whole structure of it. If anybody happened to this situation, I suggest you take it to apple store if you still in warranty. If not, First, Try that way to rest SMC and Ram. If not work, then you can pull the screen out and plug the cord into socket. There were 4 LED lights on the Motherboard. The left one will always light up when the power is connected, even under the situation that the SMC and RAM was scheduled wrong. but for my iMac, NONE is lighted up. so I replaced the Power Module. and it work again.

I was replacing my lcd screen on my late 2006 imac and while i was working on it i happened to touch the power supply the back of my lcd, then a bunch of sparks started flying everywhere. So i was wondering, would i have to just replace the power supply or would everything have to be replaced?

I was replacing my lcd screen on my late 2006 imac and while i was working on it i happened to touch the power supply the back of my lcd, then a bunch of sparks started flying everywhere. So i was wondering, would i have to just replace the power supply or would everything have to be replaced?

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Was it a Tuesday?

If it was Tuesday, you have to replace everything. But Wednesday and other days, more likely just the PSU.

That is unless it's a leap year and then it's the screen and the PSU even on Tuesdays.

(Unless there's an R in the month of course. That goes without saying.)

Got a 2008 iMac, and lately it's started to go cold when sleeping, and it won't wake up. Pull plug, wait 10 seconds, plug it back in . . . and when I push the power button I hear the fan spin up, then spin back down. Sometimes the HD will start to spin as well, but the whole thing shuts down within about two seconds. Then it won't respond to the power button unless I pull the plug, wait 10-15 seconds, and plug it back in.
Last time this happened it fired up after about 6 tries; now it's not coming to life at all.
(This is on a Saturday, waning quarter moon, Saturn in Scorpio, Patriots in first.)

Anyone got any thoughts, before I yank off the glass and start poking around?

Don't quite understand the reasoning behind shutting off the surge protector. Wouldn't you still want that active in case there is a power outage then power resumption to the house that could cause a spike coming through anything that is plug in to any socket in the house? Isn't that the point of a surge protector?

Click to expand...

Surge protectors are not "active" devices, meaning that they don't rely on being powered up to work. Most of them have metal oxide varistors (MOVs) that direct high voltages from the hot wire to the ground wire. Shutting off the surge protector disconnects the hot side, but I think it leaves the neutral side connected, and definitely leaves the ground wire still connected to the house ground.

It's arguably better than leaving the surge protector turned on, but I'd argue that if you're going to turn off the iMac *and* the surge protector, just unplug the iMac after powering it down. I just leave mine on (let it sleep) while connected to a pure sine wave UPS.

- Unplug the iMac. Hold down the power-on button, and while STILL HOLDING IT DOWN, plug the iMac into the wall outlet. Does anything change?

Hi Fishrrman (I'm brand new to MacRumors so forgive me if i haven't responded properly) I just want to thank you for this bit of info (above). In the last month my 2011 27" iMac has been really hit and miss when turning it on and this is the only info I have come across that fixes it so thank you!!

I'm also wondering if there is something I can do now that my iMac is on that will stop this problem occurring in the future?

Also, the fan is now on really loud and fast since turning the iMac back on. In the past I have reset the SMC which has worked, but this time it isn't working :0/ any ideas?

- Unplug the iMac. Hold down the power-on button, and while STILL HOLDING IT DOWN, plug the iMac into the wall outlet. Does anything change?

Hi Fishrrman (I'm brand new to MacRumors so forgive me if i haven't responded properly) I just want to thank you for this bit of info (above). In the last month my 2011 27" iMac has been really hit and miss when turning it on and this is the only info I have come across that fixes it so thank you!!

I'm also wondering if there is something I can do now that my iMac is on that will stop this problem occurring in the future?

Also, the fan is now on really loud and fast since turning the iMac back on. In the past I have reset the SMC which has worked, but this time it isn't working :0/ any ideas?

Thanks Fishrrman

Click to expand...

Hi, Did you ever work out when was wrong with your iMac? I bought one 6 months ago and Apple have had it for the last week to fix it (wouldn't turn on). They replaced the logic board and power supply and returned it to us this morning. When we tried to turn it again today, again the Mac would not turn on but this time the fan was VERY loud and fast, just as you described. I have taken it back to Apple, but just wondered if you knew what had caused your problem?

This is an old forum but I have a solution to sudden power outages. After going through the four steps instructed by Apple: Starting in Safe Mode, Resetting SMC, Resetting NVRam and reinstalling operating program almost all of the issue surrounding sudden power outages were resolved. The exception was under USERS and Groups any time I would place the cursor on the Icon (baseball) the computer would suddenly shut down. The computer also wouldn't let me see any other Icon choices in USERS and Groups other than the baseball. I finally figured out how to see other Icon choices while in safe mode and was ultimately able to select a new Icon. Once this was completed all the sudden power outages stopped.

I don't understand what the USERS and Groups Icons have to do with power on the IMAC other than a software conflict of some type. I was lucky in that I found the location which was causing our difficulties. Now the computer has worked for two days with shutting down.

If you encounter she sudden power outages try the steps recommended by Apple (Safe Mode, Resetting the SMC, Resetting the NVRam and then in this order reinstall the operating system. Instructions are available from Apple. For me these helped and allow me to diagnose the final problem with the Icon's in USERS and Groups.

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